The present invention relates to a filter press comprising two fixed stations, interconnected by a frame which is formed of at least two parallel rails on which a plurality of platforms are slidingly mounted, between which filter cloths extend, with one of said fixed posts comprising a movable head for pressing said plates against one another during the filtering step and means which are provided for spacing said plates from one another during the clearing step.
According to a known structure of such filters, the filter is provided with a single cloth which extends in zig-zag form between the different plates on the entire length of the filter. Such an arrangement has the drawback of making it difficult to stretch this single cloth in a suitable way during the filtering step and, upon breaking or using up of a portion of the cloth, making it necessary to replace the entire cloth which is, of course, a long and costly operation.
In addition, during the clearing of the plates, the filter cakes do not always fall down under the action of gravity but remain often attached to the cloth. This means that the filter cakes must be removed manually from between the pieces of the cloth.
To obviate the latter shortcoming, it has already been proposed (in the LAROX process) to use for each plate a separate cloth which forms a closed loop and which is guided on guiding and driving rollers arranged below and above each plate. In ths case the filtering takes place across the two cloth pieces which extend opposite the plate and which runs into the risk of the catching of the remaining mud particles between the cloth pieces which cannot be easily removed. Furthermore, in this known structure only one of the surfaces of each plate comprises a curved surface cooperating with the filter cloth. This leads to a reduction to half of the capacity of the filter press relative to a given number of plates. Also, in this case the soiled surface of the cloth partially gets in contact with the plane surface of the adjoining plate. Finally, the guiding means of the cloths are complex and can be applied to the technique of filter presses only with difficulty. As a matter of fact, each cloth has separate driving means, which fact leads to a complicated and expensive structure, because said means must be moved with each plate upon clearing operations and the closing of the filter.
In another known device which can only be used with vertical filter presses (method PARMENTIER), each plate is surrounded by an endless loop of filter cloth which moves on two rollers, arranged outside of the plate and comprising means for driving the cloth.
The rollers are installed, one underneath the other, in bearings, slidingly mounted in the common structure.
The rollers are thus completely independent from the corresponding plates.
The frame carries the operatively connected driving means which are controlled by pneumatic means and a motor reducing means.
In this structure also, only one surface of each plate is utilized, and the control means for the cloths and the plates are extremely complex and expensive.